kontrastmidlene

Kontrastmidlene are substances used to improve the visibility of internal body structures during medical imaging by altering the contrast between different tissues. They are commonly employed in radiography and computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound, as well as in endoscopic imaging. The aim is to make anatomy or pathology more conspicuous to radiologists and clinicians.

The main categories are iodinated contrast agents, gadolinium-based agents for MRI, and ultrasound contrast agents that consist of gas-filled microbubbles. Iodinated agents are typically water-soluble and administered intravenously or orally/rectally to illuminate vessels and organs; gadolinium-based agents are given intravenously to enhance MRI signal; ultrasound contrast uses intravenously injected microbubbles to improve echogenicity and perfusion assessment. Barium sulfate remains a widely used GI contrast in radiography but is not always grouped with iodinated agents.

Mechanisms vary by modality: iodinated contrast increases X-ray attenuation, gadolinium shortens relaxation times to boost MRI contrast, and microbubbles reflect ultrasound waves to augment signal. Administration routes depend on the clinical question and imaging type, with IV injections common across modalities and specific preparations for GI tract imaging.

Safety and regulation are important considerations. Allergic or hypersensitivity reactions can occur with iodinated and gadolinium agents. Kidney dysfunction increases the risk of contrast-induced nephropathy with iodinated agents and nephrogenic systemic fibrosis with certain gadolinium formulations. Risk mitigation includes patient screening, liver or kidney function assessment, using the lowest effective dose, selecting safer agents when possible, and adhering to professional guidelines from radiology societies.